NO309039B1 - Polymorphs of the pro-drug 6-N- (L-ALA-L-ALA) -troafloxacin - Google Patents

Description

Background for the invention

The present invention relates to a prodrug of trovafloxacin which has the formula

selected from the group consisting of polymorph PM and the monohydrate PII.M and the pseudomorph PII.PS thereof and processes for the preparation thereof. The invention further relates to methods for the use of, and pharmaceutical preparations comprising, the compounds according to the present invention, for the treatment of bacterial infections in mammals.

The antibacterial activity of trovafloxacin is described in US patent

No. 5,164,402 (the '402 patent) and 5,229,396 (the '396 patent) issued November 17, 1992 and July 20, 1993, respectively, the disclosures of which are hereby incorporated by reference in their entirety. The aforementioned patents have been transferred in the same way as the present application. A polymorph P1 of the compound of formula I and methods for its preparation are also described in the above-mentioned patents.

Summary of the present invention

In a first embodiment, the present invention relates to a prodrug of trovafloxacin having the formula

wherein said pro-drug is selected from the group comprising

a) a polymorphic PH having the following X-ray powder diffraction pattern

b) a monohydrate PII.M with the following X-ray powder diffraction pattern

; and

c) a pseudomorph PII.PS with the following X-ray powder diffraction pattern.

According to a second embodiment of the present invention, a method for the production of the prodrug Pli, as described above, is provided, which comprises treatment of the prodrug P1 of formula I, with the X-ray powder diffraction pattern below, with dry ethanol.

According to another aspect of the above embodiment, the invention provides a method for preparing the monohydrate, PII.M, as described above, of polymorph, PU, comprising a) treating polymorph P1 with an aqueous solvent;

b) treating polymorphic Pli with water; or

c) treating a pseudomorph of PII.M, PII.PS, with water.

In a further aspect of the embodiment, the present provides

invention a method for producing a pseudomorph, PII.PS, as described above, of the monohydrate PII.M. which includes vacuum drying of the monohydrate PII.M.

The invention also provides pharmaceutical compositions comprising an antibacterially effective amount of a compound of formula I, as described above, together with a pharmaceutically acceptable diluent or carrier.

In another embodiment, the invention provides a method for treating a bacterial infection in a mammal, which comprises administering to said mammal an amount of the compound of formula I, as described above, which is effective for treating a bacterial infection.

A third embodiment of the present invention provides a prodrug of trovafloxacin consisting of polymorph PH, characterized by the X-ray diffraction pattern described above, which is produced by treating polymorph Pl, characterized by the X-ray diffraction pattern described above, with dry ethanol.

According to another aspect of the above embodiment, there is provided a prodrug of trovafloxacin consisting of the monohydrate PII.M of polymorph Pli, characterized by the X-ray diffraction pattern described above, which is prepared by

a) treatment of the polymorph Pl, characterized by the X-ray diffraction pattern described above, with an organic solvent

containing water;

b) treating the polymorph Pli with water; or

c) treatment of the pseudomorph PII.PS of PII.M, with water.

Yet another aspect of the above embodiment provides a

prodrug of trovafloxacin consisting of its pseudomorph PII.PS characterized by the X-ray diffraction pattern described above, which is - prepared by vacuum drying the monohydrate PII.M.

Detailed description of the invention

The present invention relates to a prodrug of trovafloxacin, which has the formula

selected from the group consisting of a polymorph Pil and the monohydrate PII.M and the pseudomorph PII.PS thereof and pharmaceutical preparations comprising Pil, PII.M or PII.PS and methods of using them. The invention also relates to processes for the production of Pil, PII.M and PII.PS as illustrated in the following reaction scheme.

According to Scheme I, polymorph Pl is converted to polymorph Pli by treatment with dry ethanol. The conversion is suitably carried out at approx. room temperature. Polymorph P1 may be prepared according to the method of Example 49 of the '402 patent or co-pending U.S. Pat. Patent application, docket number PC9186, the description of which is hereby incorporated by reference in its entirety. The PC9186 application has been transferred in the same way as the present application. Polymorph Pli can then be converted to the monohydrate PII.M by treatment with water. The water can be in the form of liquid or steam.

Alternatively, the monohydrate PII.M can be prepared by treating polymorph Pl with organic solvents, such as (Ci-C6)alkyl esters of (Ci-C6)alkanoic acids and (Ci-C6)alkanols, containing water at a temperature from approx. ambient temperature to the reflux temperature ti) the solvent. A preferred solvent is ethyl acetate containing approx. 0.1% water and the conversion is carried out at approx. 40-50°C, preferably approx. 45°C. Excess water is removed from the product by azeotropic distillation at the reflux temperature of the solvent. Another preferred solvent is ethanol containing approx. 5% water or less. The conversion is effected by treating Pli with the solvent at its reflux temperature (ca. 78°C) and the product is recovered, as crystals, by cooling the solution.

The resulting crystals are dried to a water content of approx. 2.7% to give the desired product.

The monohydrate PII.M can be converted into a pseudomorph PII.PS by vacuum drying. The pseudomorph can be reconverted to the monohydrate by treatment with liquid water as indicated above for the conversion of Pil to

PII.M.

The antibacterial compounds of formula I, i.e. polymorph Pli, monohydrate PII.M and pseudomorph PII.PS, (hereinafter "the active compounds") which can be synthesized using the methods and intermediates of the present invention, are useful for the treatment of animals and people who have broad-spectrum bacterial infections. They are particularly useful for treating Gram-positive bacterial strains.

The active compounds can be administered alone, but will generally be administered mixed with a pharmaceutical carrier selected with regard to the particular route of administration and standard pharmaceutical practice. For example, they can be administered orally or in the form of tablets containing such additives as starch or lactose or in capsules either alone or together with additives, or in the form of elixirs or suspensions containing flavoring agents or coloring agents. For animals, they are advantageously added to animal feed or drinking water in a concentration of approx. 5 to approx. 5000 ppm, preferably approx. 25 to approx. 500 ppm. They can be injected parenterally, for example intramuscularly, intravenously or subcutaneously. For parenteral administration, they are best used in the form of a sterile, aqueous solution which may contain other solutes, for example sufficient salt or glucose to make the solution isotonic. To animals, the compounds of formula I can be administered intramuscularly or subcutaneously at dose levels of about 0.1 to approx. 50 mg/kg/day,' beneficial approx. 0.2 to approx. 10 mg/kg/day given as a single daily dose or up to 3 divided doses.

The active compounds can be administered to humans for the treatment of bacterial diseases either orally or parenterally. They can be administered orally in dose levels of approx. 0.1 to 500 mg/kg/day, advantageously 0.5-50 mg/kg/day given in a single dose or up to 3 divided doses. For intramuscular or intravenous administration, the dose levels are approx. 0.1-200 mg/kg/day, advantageously 0.5-50 mg/kg/day. While intramuscular administration can be a single dose or up to 3 divided doses, intravenous administration can involve a continuous drip. Variations will necessarily occur, depending on the weight and condition of the individual being treated, and the particular route of administration chosen, as will be known to those skilled in the art.

The antibacterial activity of the compounds according to the present invention has been shown by testing according to Steer's replicator technique, which is a standard in vitro bacterial test method described by E. Steers et al., Antibiotics and Chemotherapy, 9, 307 (1959) .

The following examples illustrate the methods and compounds of the present invention. However, it should be understood that the invention is not limited to the specifics

Example 1

L- alanvl- N- 1( 1a. 5a. 6a)- 3- f6- carboxyl- 8-( 2. 4- difluorophenyl)- 3- fluoro- 5. 8- dihydro- 5- oxo- 1, 8- naphthvridine - 2- vll- 3- azabicvchlor3. 1. 01hex- 6- v11N'- tert -butyloxycarbonylv1-L- alaninamide

The zwitterion of trovafloxacin (prepared as described in concurrent application, docket number PC9186) (3 g) was stirred with dichloromethane (45 mL) at ca. 25°C, which gave a white slurry. N-tert-butyloxycarbonyl-L-alanyl-L-alanine (2.19 g) and 2-ethoxy-1-ethoxycarbonyl-1,2-dihydroquinoline (1.95 g) were added to the slurry, and the resulting reaction mixture was stirred for 4 hours at approx. 25°C. The reaction mixture was cooled to approx. 5°C for 1 hour and the title product was isolated as white crystals by filtration. The crystals were washed with dichloromethane (ca. 15 ml) and dried under vacuum. Yield 4.7 g, 80%.

Example 2

L- alanvl- N-(( 1a. 5a. 6a)- 3- f6- carboxyl- 8-( 2. 4- difluorophenyl)- 3- fluoro- 5. 8- dihydro- 5- oxo- 1. 8- naphthvridine - 2- vn- 3- azabicvchlor 3. 1 . Olhex- 6- vlV L- alaninamide- methanesulfonate

The title compound in Example 1 (10 g) and tetrahydrofuran (60 ml) were stirred, giving a slurry at approx. 25°C. Methanesulfonic acid (2.9 g) was added to the slurry and the resulting reaction mixture was heated to reflux (ca. 66°C) for ca. 6 hours. The reaction mixture was cooled to approx. 5°C and the crystals of the title product were isolated by filtration, washed with cold tetrahydrofuran (ca. 15 ml) and dried under vacuum at 40°C. Yield 9.4 g, 94%.

Example 3

L- alanvl- N4( 1a. 5a. 6a)- 3-[ 6- carboxyl- 8-( 2. 4- difluorophenvn- 3- fluoro- 5. 8- dihydro-5- oxo- 1. 8- naphthvridine- 2 - vn- 3- azabicyclof 3. 1. 01 hex- 6- vl>- L- alaninamide methanesulfonate

The title product of Example 1 (10 g), acetone (80 ml) and water (1.8 ml) were stirred, giving a slurry at a temperature of approx. 20°C. Methanesulfonic acid (4.4 g) was added to the slurry and the resulting reaction mixture was heated to reflux (ca. 56°C) for ca. 4 hours. Additional acetone (40 mL) was added to the reaction mixture during the reflux period. The reaction mixture was cooled to approx. 5°C, and the resulting crystals of the title product were isolated by filtration, washed with cold acetone (ca.

25 ml) and dried under vacuum at approx. 35°C. Yield 9.9 g, 93%.

Example 4

L- alanvl- N- f( 1a. 5a. 6a)- 3- r6- carboxyv- 8-( 2. 4- difluorophenyl)- 3- fluoro- 5. 8- dihydro-5- oxo- 1. 8- naphthvridine - 2- vn- 3- azabicvchlor3. 1. Oihex- 6- vlVN'- tert -butloxycarbonyl- L- alaninamide

7-([1α,5α,6α]-6-amino-3-naphthyridin-2-yl]-3-azabicyclo[3,1,0]hex-3yl)-6-fluoroM-(2,4-difluorophenyl )-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylic acid-

methanesulfonate (40 g) was stirred with dichloromethane (600 ml) at approx. 20°C, which gave a white slurry. Triethylamine (7.9 g), N-tert-butyloxycarbonyl-L-alanyl-L-alanine (23.76 g) and 2-ethoxy-1-ethoxycarbonyl-1,2-dihydroquinoline (21.24 g) were added the slurry, and the resulting reaction mixture was stirred for approx. 16 hours at approx. 25°C. The reaction mixture was cooled to approx. 5°C for 1 hour, and the title product was isolated as white crystals by filtration. The crystals were washed with dichloromethane (ca. 80 mL) and dried under vacuum. Yield 42.6 g, 83%.

Example 5

Polymorphic PH of L- Ala- N-( Ma. 5a. 6a)- 3- r6- carboxyl- 8-( 2. 4- difluorophenvn- 3- fluoro- 5. 8- dihydro- 5- oxo- 1. 8- Naphthvridin- 2- vn- 3- azabicvchlor 3. 1. 01 hex- 6- vlVL-alanineamide- methanesulfonate

The title product from Example 2 or 3 was stirred in dry (water content less than about 0.1%) ethanol (2.0 ml) for 48 hours at about 25°C. The title product was isolated by filtration.

The product is characterized by the X-ray diffraction pattern described above.

Example 6

Monohvdrat of Pol<y>morph II ( PII. M)

A. The title product from Example 2 or 3 (4 g) was heated to reflux (approx. 78 °C) in ethanol containing water (<5%) (40 ml) for approx. 1 hour. A further amount of ethanol (8 ml) was added during the reflux period to obtain a solution. The reaction mixture was cooled to approx. 25°C, which gave a crystal slurry. The crystals were isolated by filtration and dried to a water content of 2.7% to give the title product. Yield 90%.

B. The title product from Example 2 or 3 (20 g) was heated to approx. 45°C in ethyl acetate (300 ml). Water (21 ml) was then slowly added to give a slurry. The slurry was heated to reflux and the water (ca. 19 mL) was removed azeotropically. The solution was cooled to approx. 25°C, which gave a crystal slurry. The crystals were isolated by filtration and dried to a water content of approx. 2.7%, which gave the title product. Yield 99%.

The title product is characterized by the X-ray diffraction pattern described above.

Example 7

Pseudomorphic PII. PS of polymorph ll-monohydrate The title product from Example 6 was dried under vacuum until all the water was removed, giving the title product. The title product is characterized by the X-ray diffraction pattern described above.

Claims (12)

1. Pro-drug of trovafloxacin, characterized by the formula where said pro-drug is a) a polymorph monohydrate PII.M with the following X-ray powder- diffraction pattern ; or b) a pseudomorph PII.PS with the following X-ray powder diffraction pattern 2. Method for the production of a pro-drug polymorph-. monohydrate PII.M of trovafloxacin of formula I, characterized in that it comprises (a) preparation of polymorph Pli with X-ray powder- the diffraction pattern by treating the prodrug polymorph Pl with the x-ray powder diffraction pattern with dry ethanol; or an organic solvent containing water; and (b) treating the polymorph Arrow with water; or treating the pseudomorph of PII.M, PII.PS, with water. 3. Method according to claim 2 step a), characterized in that said organic solvent is selected from the group consisting of (Ci-C6)alkyl esters of (Ci-C6)alkanoic acids and (Ci-C6)alkanols. 4. Method according to claim 3, characterized in that said solvent is ethyl acetate. 5. Method according to claim 2, steps (a) and (b), characterized in that it further comprises vacuum drying of the monohydrate PII.M, which gives the pseudomorph, PII.PS, thereof. 6. Process for producing a prodrug polymorph monohydrate Pli M, characterized by the X-ray diffraction pattern described above, characterized by treatment of prodrug polymorph Pl characterized by the X-ray diffraction pattern described above, with an organic solvent containing water. 7. Method according to claim 7, characterized in that said organic solvent is a C1-C5 alkyl ester of a C1-C6 alkanoic acid or a C1-C6 alkanol. 8. Method according to claim 7, characterized in that the solvent is ethyl acetate. 9. Pharmaceutical preparation for treating a bacterial infection in a mammal, characterized in that it comprises an amount of the pro-drug according to claim 1 which is effective for treating a bacterial infection, and a pharmaceutically acceptable carrier. 10. Compound according to claim 2, characterized in that it has a water content of approx. 2.7%. 11. Pro-drug of trovafloxacin, characterized in that it consists of the polymorph monohydrate PII.M, with the X-ray diffraction pattern described above, which is produced by a) treatment of the polymorph Pl, with the X-ray diffraction pattern described above, with dry ethanol or an organic solvent containing water, giving the polymorph PH with the X-ray diffraction pattern indicated above; and b) treating the polymorph Arrow with water; or treatment of the pseudomorph PII.PS, of PII.M, with water. 12. Pro-drug according to claim 11, characterized in that it consists of the pseudomorph PII.PS with the X-ray diffraction pattern described above, which is produced by vacuum drying the monohydrate PII.M.